Device for regulating pressure

ABSTRACT

A pressure regulator is provided. In one embodiment, the pressure regulator includes a body having an internal cavity for receiving a pressurized medium and inlet and outlet ports that enable a pressurized medium to enter the internal cavity at a first pressure and exit at a second pressure. The exemplary pressure regulator also includes a control piston disposed within the internal cavity that is configured to move in response to a change in pressure within the internal cavity. The pressure regulator of this embodiment also includes a damping feature within the internal cavity that is configured to oppose the movement of the control piston. Other embodiments of pressure regulators and systems are also provided.

FIELD OF THE INVENTION

The present invention relates generally to pressure regulation within asystem. More particularly, the present invention relates to a novelpressure regulating device for such systems.

BACKGROUND

This section is intended to introduce the reader to various aspects ofart that may be related to various aspects of the present invention,which are described and/or claimed below. This discussion is believed tobe helpful in providing the reader with background information tofacilitate a better understanding of the various aspects of the presentinvention. Accordingly, it should be understood that these statementsare to be read in this light, and not as admissions of prior art.

As will be appreciated, supplies of oil and natural gas have a profoundeffect on modern economies and civilizations. Devices and systems thatdepend on oil and natural gas are ubiquitous. For instance, oil andnatural gas are used for fuel in a wide variety of vehicles, such ascars, airplanes, boats, and the like. Further, oil and natural gas arefrequently used to heat homes during winter, to generate electricity,and to manufacture an astonishing array of everyday products.

In order to meet the demand for these resources, companies often spend asignificant amount of time and money searching for and extracting oil,natural gas, and other subterranean resources from the earth.Particularly, once a desired resource is discovered below the surface ofthe earth, a drilling system is often employed to access and extract theresource. These drilling systems may be located onshore or offshoredepending on the location of a desired resource. Further, such systemsinclude a wide array of components, such as valves, that controldrilling or extraction operations. Often, some of these components arecontrolled through pressure variation, such as that provided by ahydraulic control system.

In some such systems, a hydraulic pressure regulator is used to providea fluid at a regulated pressure to downstream components, such assolenoid valves. One common type of hydraulic pressure regulator has acontrol piston that moves back and forth to open and close both supplyports and vent ports of the regulator in response to the magnitude ofpressure within the regulator. As the functionality of an entiredrilling system may depend on proper operation of the hydraulic pressureregulator, it is generally desirable to employ a pressure regulator thatis both durable and sensitive to changes in pressure. Further, when sucha regulator is employed in a subsea application, halting production fromthe system to replace an underwater pressure regulator may beparticularly undesirable.

There is a need, therefore, for a pressure regulator that providesincreased sensitivity to changes in pressure within the regulator andincreased reliability.

SUMMARY

Certain aspects commensurate in scope with the originally claimedinvention are set forth below. It should be understood that theseaspects are presented merely to provide the reader with a brief summaryof certain forms the invention might take and that these aspects are notintended to limit the scope of the invention. Indeed, the invention mayencompass a variety of aspects that may not be set forth below.

Embodiments of the present invention generally relate to a novelpressure regulator. In certain embodiments, the pressure regulator is ahydraulic pressure regulator configured for use in controllingcomponents of a drilling system. In one embodiment, the exemplarypressure regulator has a plurality of internal pistons, including twopistons that operate independently of one another to open and closerespective ports of the regulator. In another embodiment, the pressureregulator includes an internal damping feature for enhancing stabilityof the pressure regulator. In an additional embodiment, the pressureregulator includes a seal plate having an aperture that is partiallyshaped in accordance with the geometry of a respective portion of amating seal ring. In yet another embodiment, the pressure regulator mayinclude a torque-reducing adjustment mechanism that allows adjustment inthe amount of biasing force applied to a piston within the pressureregulator by a load spring without applying a substantial rotationalforce to the load spring. In a further embodiment, the pressureregulator includes an apparatus for venting control fluid out of a mainbody of the pressure regulator, through a conduit, and into a separatechamber within the pressure regulator to flush contaminants, liquids, orotherwise undesirable materials from the separate chamber. Additionalembodiments of the present invention may also include variouscombinations of the features noted above.

Various refinements of the features noted above may exist in relation tovarious aspects of the present invention. Further features may also beincorporated in these various aspects as well. These refinements andadditional features may exist individually or in any combination. Forinstance, various features discussed below in relation to one or more ofthe illustrated embodiments may be incorporated into any of theabove-described aspects of the present invention alone or in anycombination. Again, the brief summary presented above is intended onlyto familiarize the reader with certain aspects and contexts of thepresent invention without limitation to the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a block diagram of an exemplary resource extraction systemhaving a pressure regulator in accordance with one embodiment of thepresent invention;

FIG. 2 is a perspective view of an exemplary pressure regulator inaccordance with one embodiment of the present invention;

FIG. 3 is a cross-sectional view of the pressure regulator of FIG. 2,illustrating exemplary internal components of the pressure regulator inaccordance with one embodiment of the present invention;

FIG. 4 is an axial cross-sectional view of the pressure regulator ofFIG. 3;

FIG. 5 is a detailed sectional view of the pressure regulator of FIG. 3including two internal pistons in accordance with one embodiment of thepresent invention;

FIG. 6 is another detailed sectional view of the pressure regulator ofFIG. 3, illustrating the closing of supply ports of the pressureregulator in accordance with one embodiment of the present invention;

FIG. 7 is an additional detailed sectional view of the pressureregulator of FIG. 3, illustrating the opening of vent ports of thepressure regulator in accordance with one embodiment of the presentinvention;

FIG. 8 is a perspective view of an exemplary seal plate of the pressureregulator of FIG. 3 in accordance with one embodiment of the presentinvention;

FIG. 9 is a sectional view of the exemplary seal plate of FIG. 8;

FIG. 10 is a detailed sectional view of the pressure regulator of FIG.3, illustrating a damping feature disposed within the pressure regulatorin accordance with one embodiment of the present invention;

FIG. 11 is a detailed sectional view of the pressure regulator of FIG.3, illustrating a load spring adjustment mechanism in accordance withone embodiment of the present invention; and

FIG. 12 is a cross-sectional view of an exemplary pressure regulatorhaving an apparatus for flushing a spring chamber within the pressureregulator in accordance with one embodiment of the present invention.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

One or more specific embodiments of the present invention will bedescribed below. In an effort to provide a concise description of theseembodiments, all features of an actual implementation may not bedescribed in the specification. It should be appreciated that in thedevelopment of any such actual implementation, as in any engineering ordesign project, numerous implementation-specific decisions must be madeto achieve the developers' specific goals, such as compliance withsystem-related and business-related constraints, which may vary from oneimplementation to another. Moreover, it should be appreciated that sucha development effort might be complex and time consuming, but wouldnevertheless be a routine undertaking of design, fabrication, andmanufacture for those of ordinary skill having the benefit of thisdisclosure.

When introducing elements of various embodiments of the presentinvention, the articles “a,” “an,” “the,” and “said” are intended tomean that there are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements.Moreover, the use of “top,” “bottom,” “above,” “below,” and variationsof these terms is made for convenience, but does not require anyparticular orientation of the components.

Turning now to the present figures, an exemplary drilling system 10 isillustrated in FIG. 1 in accordance with one embodiment of the presentinvention. Notably, the exemplary system 10 facilitates extraction of aresource, such as oil or natural gas, from a well 12. The exemplarysystem 10 includes a variety of equipment, including surface equipment14, riser equipment 16, and stack equipment 18, for extracting theresource from the well 12 via a wellhead 20. The exemplary system 10 maybe employed in a variety of drilling or extraction applications,including onshore and offshore, i.e., subsea, drilling applications. Inone subsea resource extraction application, the surface equipment 14 ismounted to a drilling rig above the surface of the water, the stackequipment 18 is coupled to the wellhead 20 proximate the sea floor, andthe various equipment 14 and 18 is coupled to one another via the riserequipment 16.

As will be appreciated, the surface equipment 14 may include a varietyof devices and systems, such as pumps, power supplies, cable and hosereels, control units, a diverter, a gimbal, a spider, and the like.Similarly, the riser equipment 16 may also include a variety ofcomponents, such as riser joints, fill valves, control units, and apressure-temperature transducer, to name but a few. The riser equipment16 facilitates transmission of the extracted resource to the surfaceequipment 14 from the stack equipment 18 and the well 12.

The stack equipment 18 also includes a number of components, such asblowout preventers and/or production or “Christmas” trees, forextracting the desired resource from the wellhead 20 and transmitting itto the surface equipment 14 and the riser equipment 16. In the presentlyillustrated embodiment, operation of the stack equipment 18 iscontrolled by an exemplary control system 22. The exemplary controlsystem 22 includes a pressure regulator 24 and a plurality of valves 26that control flow through the system 10. In some embodiments, one ormore of the plurality of valves compose a portion of a blowout preventeror Christmas tree.

Further, in an exemplary embodiment, the pressure regulator 24 is ahydraulic pressure regulator and the plurality of valves 26 includessolenoid valves. As will be appreciated, valves 26 may be configuredwith a specific pressure rating, such as 3,000 psi. Often, in hydraulicsystems, an initial supply pressure is provided to the control system22, such as from a bank of accumulator tanks, that is higher than thepressure rating of various system components, such as valves 26, tofacilitate maintenance of adequate pressure to the system componentseven during periods of high usage. In the exemplary system 10, thepressure regulator 24 enables management of the supply pressure todeliver a regulated pressure to downstream components, such as valves26. While the pressure regulator 24 of the presently illustratedembodiment is a component of the stack equipment 18, it will beappreciated that, in other embodiments, the pressure regulator 24 may bedisposed in other portions of the system 10, such as a component of thesurface equipment 14, in full accordance with the present techniques.Additionally, certain embodiments may include multiple pressureregulators 24, which may be configured to receive and transmit controlfluid at the same respective pressure levels as each other or,alternatively, such that two pressure regulators 24 each receive and/ortransmit fluids at pressure levels that are different between the tworegulators 24.

An exemplary pressure regulator 24 is illustrated in FIG. 2. Thepressure regulator 24 includes an elongated housing or body 30 having anupper housing 32 and a lower housing 34 for receiving various internalcomponents, as discussed in greater detail below. Upper and lower endcaps 36 and 38 are secured to the lower housing 34, and an end cap 40 issecured to the upper housing 32, to enclose the aforementioned internalcomponents within the body 30. In the presently illustrated embodiment,the end caps 36 and 38 are secured to the lower housing 34 via aplurality of fasteners 42. While fasteners 42 of the presentlyillustrated embodiment are bolts that pass through the end caps 36 and38 and into the lower housing 34, it should be noted that the end caps36 and 38 may be secured to the lower housing 34 in a variety of othermanners, including the use of latches, other mechanical fasteners,magnets, adhesives, welding, or any other suitable technique.

The pressure regulator 24 also includes a pair of supply assemblies 44disposed on opposite sides of the lower housing 34, and a pair of ventassemblies 46, which are also disposed on opposite sides of the lowerhousing 34 from one another. The supply and vent assemblies 44 and 46may be secured to the lower housing 34 in any suitable fashion, such asby fasteners 42. While the exemplary pressure regulator 24 includes apair of both supply pressure assemblies 44 and vent pressure assemblies46, it should be noted that a different number of such assemblies mayinstead be employed in full accordance with the present techniques.

During operation, a control medium at a first pressure, such as 5,000psi, may enter the pressure regulator 24 through the supply ports 48 ofthe supply assemblies 44, and the control medium may be output at asecond, regulated pressure, such as 3,000 psi, via an regulated pressureoutlet port 50 disposed in a side of the lower housing 34. Additionally,if the pressure inside the regulator 24 exceeds a certain threshold, thecontrol medium may be vented from the regulator 24 through the ventports 52 of the vent assemblies 46. In the presently illustratedembodiment, the pressure regulator 24 is a hydraulic pressure regulatorand the control medium includes hydraulic fluid. In other embodiments,however, the control medium may be some other material, such as apressurized gas. Consequently, while the instant description of theillustrated embodiments may refer to a control fluid, it will beappreciated that such description may apply to a control liquid in ahydraulic pressure regulator in accordance with one embodiment of thepresent invention, and does not necessarily preclude the use of agaseous control medium in an alternative embodiment.

The internal operation of the exemplary regulator 24 may be betterunderstood with reference to FIGS. 3 and 4, which are sectional views ofthe exemplary regulator 24 illustrated in FIG. 2. Notably, asillustrated in FIG. 3, the lower housing 34 generally defines twointernal chambers: a supply chamber 60 and a vent chamber 62. A supplypiston 64 is disposed within the supply chamber 60, extends through theupper end cap 36, and is biased by a supply load spring 66 disposedwithin the upper housing 32. Similarly, a vent piston 68 is disposedwithin the vent chamber 62, extends through the supply piston 64 and theupper end cap 36, and is biased by a vent load spring 70. In thepresently illustrated embodiment, the vent piston 68 extends through thesupply piston 64 and the load springs 66 and 70 are disposed concentricto one another in the same portion of the upper housing 32. However, inother embodiments, the springs 66 and 70 may be located apart from oneanother, and the vent piston 68 may have a configuration in which itdoes not extend through the supply piston 64 or the upper end cap 36 infull accordance with the present techniques.

As discussed in greater detail below, pressure within the supply andvent chambers 60 and 62 may apply a thrust force to the supply piston 64and/or the vent piston 68 that acts against the biasing force providedby springs 66 and 70, respectively, such that supply ports 48 and ventports 52 may be opened and closed. The biasing force supplied by springs66 and 70 can be modified via a spring load adjustment mechanism 72disposed at one end of the upper housing 32 and discussed in greaterdetail below. As may be appreciated, the exemplary regulator 24 includesvarious seals or O-rings 74, disposed between the components to maintainpressure within the regulator 24 and reduce or prevent leakage ofmaterials, such as a control fluid, from or into the interior ofregulator 24.

An axial sectional view of the exemplary regulator 24 is provided inFIG. 4. During operation, when the supply ports 48 are open, the controlmedium or fluid enters the supply ports 48, as generally indicated byarrows 76. This control fluid is routed into the supply chamber 60 andabout the supply piston 64, as generally indicated by arrows 78. Thecontrol fluid may then be output at a regulated pressure to downstreamcomponents through the outlet port 50, as generally indicated by arrow80.

The opening and closing of the supply ports 48 and vent ports 52 may bebetter understood with reference to the detailed sectional views ofFIGS. 5-7. In the presently illustrated embodiment, the flow of controlfluid or medium into the regulator 24 through the supply ports 48 isgenerally controlled by motion of the supply piston 64. Moreparticularly, in one embodiment, supply shear seal rings 84 are disposedwithin recesses 86 of the supply piston 64. Springs 88 are also disposedwithin the recesses 86 to bias the supply shear seal rings 84 againstsupply seal plates 90 of the supply assembly 44. The exemplary supplyseal plates 90 include a first fluid passageway 92 and a second fluidpassageway 94 that facilitate flow of a control fluid through supplyports 48 to the supply chamber 60.

A control fluid entering the supply chamber 60 may pass to the ventchamber 62 through a separating shoulder 104 via a plurality of pressuretransfer ports 106. In the present embodiment, vent shear seal rings 108are disposed within a recess 110 of the vent piston 68. The vent shearseal rings 108 are similarly biased by a spring 112 against a pair ofvent seal plates 114. The vent seal plates 114 also include first andsecond fluid passageways 116 and 118, respectively, which enable fluidto be vented from the vent chamber 62 through the vent ports 52. In thepresently illustrated embodiment, the vent seal rings 108 are of adifferent size than the supply seal rings 84. Further, the exemplarysecond passageways 94 and 118 of the seal plates 90 and 114,respectively, are also of different sizes than one another and are basedon the particular sizes and geometries of the seal rings 84 and 108, asdiscussed in greater detail below.

An initial operating state is depicted in FIG. 5, in which the supplyports 48 are open and the vent ports 52 are closed with respect to theinterior of the pressure regulator 24. This configuration allows thecontrol medium to enter the pressure regulator 24 through the supplyports 48 and exit through the regulated pressure outlet port 50, asdiscussed above. As will be appreciated, hydraulic or pneumatic pressurewithin the supply chamber 60 results in a thrust force applied to thesupply piston 64 in the direction generally indicated by arrow 96.However, the biasing force of supply load spring 66, the frictionbetween the shear seal rings 84 and seal plates 90, and the frictionattributable to the seal 74 between the supply piston 64 and the upperend cap 36 each oppose movement of the piston in the direction indicatedby arrow 96. If the thrust generated by the pressure within the supplychamber 60 is below a first pressure threshold (which is generallydictated by the frictional and biasing forces noted above), the supplyports 48 remain open to allow additional control fluid to enter thepressure regulator 24 and exit through the outlet port 50. In anexemplary embodiment, the first pressure threshold may be substantiallyequal to a desired operating pressure of downstream components, such as3,000 psi.

As the pressure downstream and within the regulator 24 increases andapproaches the first pressure threshold, the hydraulic force on supplypiston 64 becomes sufficient to move the supply piston 64 in thedirection indicated by arrow 96 and toward the closed position generallyillustrated in FIG. 6. Particularly, in the presently illustratedembodiment, the supply load spring 66, the seal rings 84, and the supplypiston 64 are configured such that the seal rings 84 are moved into afully closed position, in which the seal rings 84 are disposed over theentirety of the second fluid passageway 94, when the pressure within thesupply chamber 60 reaches and/or exceeds the first pressure threshold.At this point during operation, the pressure regulator may be consideredto be in a state of equilibrium, in which both the supply and vent ports48 and 52 are closed and no control medium flows through the regulator24. In other words, at this operational point, the pressure inside thesupply and vent chambers 60 and 62 is above the first pressurethreshold, causing the supply piston 64 to move into a closed position,but is not sufficient to transmit a thrust to the vent piston 68 thatresults in opening of the vent ports 52.

As may be appreciated, as the pressure within the pressure regulator 24continues to increase beyond the first pressure threshold, the thrustapplied to the vent piston 68 by the internal pressure also increases,causing the vent piston 68 to move in the direction indicated by arrow96. As the internal pressure reaches a second pressure threshold, thevent piston 68 and vent seal rings 108 are moved into an open position,as generally illustrated in FIG. 7, which allows control fluid withinthe vent chamber 62 to be vented out of the pressure regulator 24 viavent ports 52.

It will be noted that, in the presently illustrated embodiment, thesupply piston 64 and the vent piston 68 may operate independent of oneanother. That is, movement of the supply piston 64 and supply seal rings84 to control flow through the supply ports 48 is independent of themovement of vent piston 68 and vent seal rings 108 that generallycontrol flow through the vent ports 52. The independent operation of thesupply and vent piston 64 and 68 enable the use of two separate loadsprings 66 and 70 that may be specifically configured for a desiredrange of regulated and vent pressures, respectively. Further, themechanical independence of supply piston 64 and vent piston 68 reducesthe frictional forces that act against the thrust force applied to eachpiston by the internal pressure of the pressure regulator 24, andthereby enhances the sensitivity of the pressure regulator 24.

In other words, while a single piston carrying both seal rings 84 andseal rings 108 would experience frictional forces attributable to bothsets of the seal rings 84 and 108, the supply and vent pistons 64 and 68in the presently illustrated embodiment are subjected to only thefrictional force attributed to their own respective seal rings 84 and108 (in addition to any friction created by other components, such asseals 74). Consequently, the supply piston 64 and the vent piston 68 areeach more responsive to a sudden increase or decrease in the pressurewithin the supply chamber 60 and the vent chamber 62. For example, inthe general state of equilibrium illustrated in FIG. 6, a suddenincrease in pressure within the regulator body 30, such as that causedby a sudden closing of a downstream valve, causes only the vent piston68 and its associated seal rings 108 to be moved into the open positiongenerally illustrated in FIG. 7, to relieve the pressure buildup withinthe pressure regulator 24. Similarly, the pressure regulator 24 may morequickly open the supply ports 48, such as by moving only the supplypiston 64 and the seal rings 84, to allow additional control fluid toenter the supply chamber 60 to compensate for a sudden drop in internalpressure.

In certain embodiments, the supply seal plates 90 may be specificallyconfigured based on the geometries of their respective seal rings 84.For instance, in the embodiment illustrated in FIGS. 8 and 9, anexemplary supply seal plate 90 includes an arcuate opening or aperture128 defined by the exit of the second passageway 94 at a surface 130 ofthe supply seal ring 90. As will be appreciated, a shear supply sealring 84 (FIG. 5) may operate to selectively cover and uncover thearcuate opening 128 to control flow through the fluid passageways 92 and94, as discussed above. Notably, the exemplary arcuate opening 128includes curved inner and outer edges 132 and 134, respectively. Incertain embodiments, the shape of the aperture 128 is related to theshape of a respective seal ring 84. For instance, in one embodiment, thecurved outer edge 134 of the aperture 128 has a rate of curvature thatis substantially identical to that of an inner circumference orperimeter of a lip of the seal ring 84 such that a portion of the inneredge or perimeter of the seal ring 84 is substantially coincident withthe curved outer edge 134 when pressure within the pressure regulator 24is substantially equal to the first pressure threshold. In someembodiments, the curved inner edge 132 may have a rate of curvature thatis substantially identical to the outer circumference of the seal ring84. Other configurations in which the curved inner and outer edges 132or 134 are configured based on other surfaces of the seal ring 84 arealso envisaged.

Similarly, a vent seal plates 114 (FIG. 5) may also include an aperturethat includes an edge coincident to an edge of a vent seal ring 108 whenpressure within the regulator 24 is substantially equal to the secondpressure threshold. While the seal plates 90 and 114 may besubstantially identical to one another in some embodiments, theapertures of the seal plates 90 and 114 may instead have different sizesor geometries than one another to provide different flow rates throughtheir respective passages and to match differences in the geometries ofseal rings 84 and 108.

Certain embodiments of the present invention may also include a dampingfeature, such as that illustrated in FIG. 10, which may enhancestability of the pressure regulator 24. As may be appreciated, suddenincreases or decreases in pressure within a system having the exemplarypressure regulator 24 may, in some instances, result in an undesirablelevel of fluid-structure interaction that decreases stability within thesystem. The exemplary damping feature illustrated in FIG. 10 may reducethe magnitude of such interaction. In one embodiment, the dampingfeature includes a recess or damping chamber 140 formed in the end cap36 and configured to receive a mating feature 142 of the supply piston64. As will be appreciated, the mating feature 142 may be secured to orintegral with the supply piston 64. Notably, the mating feature 142 isconfigured to fit within the damping chamber 140 and provides anenhanced cross-sectional area that increases drag on the supply piston64 as it moves within the supply chamber 60. Additionally, in oneembodiment, the mating feature 142 includes a surface that is generallyperpendicular to the longitudinal axis of the supply piston 64.

For instance, as pressure within the supply chamber increases, thesupply piston 64 moves in the direction indicated by arrow 96 andreduces the available space within the damping chamber 140 for thecontrol medium or fluid. Thus, the interaction between movement of thesupply piston 64 and the damping chamber 140 forces control fluid withinthe chamber 140 to either pass through the mating feature 142 via one ormore bleed ports 144 or around the outer circumference of the matingfeature 142. Further, in one embodiment, a guide ring 146 may bedisposed about the outer perimeter of the mating feature 142 to furtherinhibit flow of the control fluid around the outer perimeter. In oneembodiment, the interaction of the damping chamber 140 and the matingfeature 142 substantially reduces or prevents the undesirable effects offluid-structure interaction within the pressure regulator 24.

Additionally, one or more embodiments of the present invention may alsoinclude an exemplary spring load adjustment mechanism 72, as generallyillustrated in FIG. 11. In the presently illustrated embodiment, theadjustment mechanism 72 includes an adjustment screw or member 154 thatis coupled to the end cap 40 and extends into the upper housing 32.Further, the adjustment screw 154 includes threads that engage a plunger156. The exemplary plunger 156 includes dowels or pins 158, disposedwithin recesses 160, which extend from the plunger 156 and intocorresponding slots 162 formed within the upper housing 32. The pins 158cooperate with the slots 162 to prevent rotation of the plunger 156within the upper housing 32. The engagement of the adjustment screw 154with the plunger 156 facilitates the increasing and decreasing of thebiasing forces applied to supply and vent piston 64 and 68 (FIG. 3).Particularly, in one embodiment, rotation of the adjustment screw 154 inone direction causes axial motion of the plunger 156 in the directiongenerally indicated by arrow 164, thereby increasing the biasing forcesapplied to the pistons by their respective load springs 66 and 70.Similarly, rotation of the adjustment screw 154 in the oppositedirection results in an axial movement of the plunger 156 in thedirection generally indicated by the arrow 166. Because the plunger 156includes an anti-rotation feature, rotation of the adjustment screw 154generally does not transmit a torque to the load springs 66 and 70 orthe pistons 64 and 68. In an alternative embodiment, an adjustmentmechanism that allows independent adjustment of each of the load springs66 and 70 is envisaged.

Further, in one embodiment, an exemplary pressure regulator 24 includesan apparatus for flushing the interior of the upper housing 32. Notably,the exemplary pressure regulator 24 includes a fluid conduit 172 thatconnects a vent port 52 with an inlet port 174 formed in the end cap 40.The fluid conduit 172 may be generally defined by couplings 176 and 178secured to the vent port 52 and inlet port 174, respectively, and a hoseor pipe 180 that extends between the coupling 176 and 178. As the ventports 52 are opened, the control fluid being vented from the ventchamber 62 may be routed through the fluid conduit 172 and into achamber 182 in which the load spring 66 and 70 are disposed. As may beappreciated, the fluid injected into the spring chamber 182 may passthrough or around the plunger 156, such as through flow ports formed inthe plunger 156 or the grooves 162. This pressurized fluid is thenrouted through the chamber 182 and exits the chamber through the bleedports 184 disposed at one end of the upper housing 32. In one embodimentrelated to subsea operation of the exemplary pressure regulator 24, therouting of control fluid through the fluid conduit 172 and the springchamber 182 may flush sea water from the spring chamber 182, therebyreducing or preventing growth of marine life within the spring chamber182. In one embodiment, check valves may also be added to the bleedports 184 to prevent sea water from entering the spring chamber 182.

While the invention may be susceptible to various modifications andalternative forms, specific embodiments have been shown by way ofexample in the drawings and have been described in detail herein.However, it should be understood that the invention is not intended tobe limited to the particular forms disclosed. Rather, the invention isto cover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention as defined by the followingappended claims.

1. A pressure regulator comprising: a housing including a first innervolume and a second inner volume, the housing having an inlet port andan outlet port to facilitate flow of a control medium through the firstinner volume, wherein the housing fluidly isolates the first innervolume from the second inner volume; a piston disposed within the firstinner volume and responsive to a change in pressure within the firstinner volume, wherein the piston is configured to open the outlet portto vent the control medium from the first inner volume if the pressurewithin the first inner volume reaches a threshold pressure; and aconduit external to the housing and extending from the outlet port to anadditional inlet port that is in fluid communication with the secondinner volume through the housing, wherein the conduit enables fluidcommunication between the first and second inner volumes such that thecontrol medium vented through the outlet port is routed outside of thehousing through the conduit, into the second inner volume from theconduit via the additional inlet port, and out of the second innervolume through a bleed port in an exterior surface of the housing, andwherein the additional inlet port and the bleed port are located atopposite first and second ends of the second inner volume to enable flowof the vented control medium through the second inner volume from theadditional inlet port at the first end of the second inner volume, byone or more components disposed within the second inner volume, and outthe bleed port at the opposite second end of the second inner volume toflush water from the second inner volume during submerged operation ofthe pressure regulator.
 2. The pressure regulator of claim 1, comprisinga plurality of pistons disposed within the first inner volume.
 3. Thepressure regulator of claim 1, wherein a biasing spring is disposedwithin the second inner volume.
 4. A pressure regulator comprising: ahousing including a first inner volume and a second inner volume, thehousing having an inlet port and an outlet port to facilitate flow of acontrol medium through the first inner volume, the housing including: afirst housing portion having the inlet port and the outlet port, and atleast partially defining the first inner volume; an end cap coupled tothe first housing portion; and a second housing portion coupled to theend cap and at least partially defining the second inner volume; apiston disposed within the first inner volume and responsive to a changein pressure within the first inner volume, wherein the piston extendsthrough the end cap into the second inner volume and the piston isconfigured to open the outlet port to vent the control medium from thefirst inner volume if the pressure within the first inner volume reachesa threshold pressure; a seal disposed about the piston to facilitatefluid isolation of the second inner volume from the first inner volumewhile permitting motion of the piston through the end cap; and a conduitexternal to the housing and extending from the outlet port to anadditional inlet port that is in fluid communication with the secondinner volume through the housing, wherein the conduit enables fluidcommunication between the first and second inner volumes such that thecontrol medium vented through the outlet port is routed outside of thehousing through the conduit, into the second inner volume from theconduit via the additional inlet port, and out of the second innervolume through a bleed port in an exterior surface of the housing. 5.The pressure regulator of claim 4, wherein a first end of the secondhousing portion is coupled to the end cap, and an opposite second end ofthe second housing portion is coupled to an additional end cap of thehousing.
 6. The pressure regulator of claim 5, wherein the bleed port islocated at the first end of the second housing portion proximate the endcap, and the additional inlet port is located within the additional endcap.
 7. The pressure regulator of claim 4, wherein the pressureregulator is configured to operate in a subsea environment and to expelsea water entering the second inner volume from the subsea environmentto inhibit growth of marine life within the second inner volume.